Hot Tapping on a Seamed Pipe

"Is it allowed to hot tap on a seamed pipe by welding the branch connection across the seam weld?"

Short answer is not allowed.

For a fool like you that still does not know how to safely perform a hot tap, go ahead and torch into that natural gas main. I look forward to your acceptance of a Darwin Award.

You really, really, really need to purchase a set of pipeline specifications from ASME and learn how to use them.

I have to agree with Fred. Your level of inexperience (or helplessness) is obvious by the type of help you are seeking here. And the numerous questions you have asked before which all indicate that you are a novice.

No competent engineer would ever ask such questions of strangers, and then take their advice and put it into practice.

Where is your safety officer? Where is your mechanical engineer? Where is your hot tapping expert?

Get some COMPETENT help.

I work in a steel mill. I am not directly involved with pipe fitting but often talk to pipe fitters. Those who do hot taping were trained by their predecessors who were trained by their predecessors etc. I recently asked about finding the seam on a seamed pipe and was told that it did not matter. I have since learned that they were wrong but that is how it is done. We mostly do hot taping on nitrogen lines and water lines that are usually operating well below pressures they are capable of but it is a bad practice. I am not engineering these jobs or supervising them but just curious. clperera may be in a similar situation.

Seamly would be unseemly; unseamly would be seemly.

It seamed so, to me.

If you weld on a seam on a pipe you make it weaker, the only way to minimize would be to heat treat it, and since it is in operation it would not be possible so the short answer is NO.

Wow this is really insulting. I thought people came here for engineering advice not just to be insulted.

I don't understand. Is everyone's objection to this for welding on a gas line? That makes me wonder if any of you have ever performed a hot tap.

Check out the link below. I don't advice that you do the procedure but it sounds like it can be done. My advice: read the website I linked, look at the appropriate sections of ASME B31.8 and API 2201 (probably read all of API 2201), and then consult an experienced mechanical engineer.

Under API 2201 Section 6.8:

Welding or hot tapping should not be permitted closer than

18 in. (46 cm) to a flange or threaded connection, or approximately

3 in. (8 cm) to a welded seam (including a longitudinal

seam of welded piping) unless determined by an

engineering review to be acceptable.

EPA link:

http://www.epa.gov/gasstar/documents/ll_hottaps.pdf

Please feel free to tutor this individual as much as you want. He's not after advice. He should already know how to perform the operation, or where to find technical assistance that has some validity and is recognized by the permitting organization. Not, "Oh I got this information from strangers on the internet. Credentials????? How would I know. It's an anonymous forum".

If you look at the past questions posed by this person, you will find that they know little or nothing about the topics and could very well kill people by not knowing what they are doing.

I'm sure they will be grateful for your tutoring.

They should hire an engineer who knows what they are doing.

Cheers!

I understand your concern but I've also been in the position of an in-plant project engineer/project manager. Small plants, especially, don't have the type of technical expertise that's always required.

This might be an electrical engineer that's being asked to manage a project to hot tap a line. His inspector may have raised a concern without having knowledge to direct him.

He might not be competent in this field but telling his boss "I'm not going to manage this project because I'm an electrical engineer" is not a good way to keep his job.

There's a difference in responses of "You're incompetent so I don't want to deal with you" and "look at these standards and then consult an expert."

If I were asked to perform this, and knew nothing about it, I would refuse, period. Any responsible engineer would refuse, also. I'd rather be unemployed than responsible for killing people.

If you would have them accept the "advice" of total strangers, with absolutely no assurance that these total strangers know ANYTHING about the subject at hand, I say that's totally irresponsible of you, and the OP.

Cheers.

Irresponsible to perform the calculations or manage the project? You don't have to be competent in that area to manage a budget and schedule. Or even to make sure the quality is up to par.

I don't see how it's irresponsible to give the OP code references and say to contact an expert. It seems more irresponsible to assume that insulting the OP will make him give up and not do the project.

Working in an engineering firm has taught me that you can't force someone to build something that's technically sound. All you can do is inform them of the right way to do things and hope they do it.

So if we were asked "Is it safer to make 10 liters of nitroglycerin or 50 kilograms of C4 and how does one make this?" you would find it acceptable to answer all parts of this question and hope the person understands how to safely use these chemicals. Just because we can provide an answer does not mean we should provide an answer.

Anyone that appears to me to not respect the safety of others will be insulted and hopefully driven away by me.

Yes, this is really insulting. Hot tapping is a dangerous process that can only be done safely with the authority of the owner of the pipe and by properly trained individuals using recognized equipment to industry standards. CR4 is not the source for education on hot tapping and has no authority to provide any kind of advice. Because of the multiple ways that a leaking pipeline can impact an area, the risk of all operations to a pipe must be methodically managed by government agencies and those who own the pipe.

I have no problem with a qualified individual that knows the pipe material that meets inspection standards from welding at all. I just do not want CR4 to be at all involved with anything resembling the 2010 San Bruno incident.

I hate to tell you this but there's currently nothing stopping the OP from running with this work regardless of his competence or what we say on here. I think if you really wanted to help prevent a catastrophe, you could point the OP in the right direction instead of insulting him.

I don't know about everyone else, but when I come across a problem that I have little knowledge on, I come to CR4 to look for direction. I'm hoping that maybe someone with experience can tell me which code or book to look in to quickly narrow my search.

Please define a "qualified individual." I've checked the calculations of vessel vendors and found numerous mistakes on a consistent basis. If I had no knowledge of which code to look at, then I would just trust that this "qualified individual" had done the proper calculations and work. Personally, I have no problem with the OP trying to educate himself before taking on this task. I hope that he still looks for an expert though.

"Yes, it is frustrating when an OP does not provide enough information for us to solve a problem. Remember, the OP doesn't know how to solve their problem. The OP does not know which parts of their system must be known to diagnose the failure or undesired result. The OP is not a teacher providing an exam question with all the information needed to solve a problem. We can entice the OP to provide us the pertinent information by showing some of our knowledge or drive them away with sarcasm and ridicule. Sometimes how the OP has phrased their question, they should not be attempting to work on their problem. In even these cases it is far better to get the OP to realize that they are not qualified to safely work on their problem than it is to just drive them away.

We also should learn to tolerate this frustration since this is a public forum. Nobody is obligated to return to us with any additional information, let alone any gratitude. Nobody must qualify to post here. So all levels of skills will arrive here."

~Redfred~

I am also known for deliberately stepping on toes of those who try to enter realms they have no safe business being in. When it comes to safety, I have been very consistent. I do recognize that my safety comments have been misunderstood, but I do correct them when needed.

It should be obvious the OP doesn't know what he is doing.

It should be equally obvious some of the responders are equally as ignorant.

"Is it allowed to hot tap on a seamed pipe by welding the branch connection across the seam weld? Our problem is if we have to avoid the seam the branch has to be welded horizontal as the longitudinal weld seam is on the top of the pipe. Thank you in advance."

I see no mention of the process being NG or any other type of gas.

Joshi- It could be allowed. After an engineering study has been completed.

Fred- Do you use a torch to hot tap? No N2 sweep? You would have been better off advising of the danger of dropping the coupon.

Lyn- como siempre, true but harsh.

Varg- Wrong, wrong, and wrong. Does no one PWHT? Where are your calcs? No?

Cingold- Good work, as usual.

Clperera- It can be done. As I am sure you have heard many times before, consult a qualified Engineer for calculations and details. You are likely going to need to: preheat before and post weld heat treat the connection after. Again, a qualified Engineer will need to be consulted for details. BTW, hot tapping vertical down will drop cuttings into your process and increases the risk of loosing the coupon into the pipe. These problems cause hot taps to be considered an absolute last resort.

Take care,

-A-

See ASME PCC-2-2018, 216-3.6 Hot tap location.